The production process of a semiconductor device such as a memory IC, a logic IC, or a system LSI includes the step of forming an interlayer insulating film and the like. In these steps, a flattening technique is adopted, if required. Therefore, the CMP enabling satisfactory flattening is receiving attention.
In the course of the CMP, a slurry in which grains of silica, ceria, alumina, or the like are dispersed in an aqueous solvent or the like are supplied to an insulating film. The surface of the insulating film immediately after the completion of the CMP is contaminated with polishing waste, components derived from the slurry, and the like. These contaminants have adverse effects on the electrical characteristics of a semiconductor device, so that it is necessary to remove the contaminants by cleaning and rinsing. As the cleaning solution used in the cleaning step after the CMP, for example, the following detergent compositions are disclosed (see, for example, Patent Literatures 1-4).
Patent Literature 1 discloses a detergent composition that contains a water-soluble polymer with a particular weight-average molecular weight (e.g., 1000 to 100000) and NR4OH (R is a hydrogen atom or an alkyl group with a carbon number of 1-6) and that is used for cleaning a wiring board after the CMP.
Patent Literature 2 discloses a detergent composition that contains an organic acid such as acetic acid, an organic alkali component ((R)4N+OH−, where R1 is a hydrogen atom, a hydroxyl group, an alkoxy group, or an alkyl group that may be replaced by halogen), an anionic surfactant such as alkylsulfonic acid or a salt thereof, and water, and that is used for cleaning the surface having metal wiring after the CMP.
Patent Literature 3 discloses a detergent composition that contains a nonionic surfactant and water, and that is used for cleaning the surface having metal wiring after the CMP.
Patent Literature 4 discloses a detergent composition that contains at least one selected from the group consisting of a sulfonate (R1SO3M1), a sulfuric ester salt (R2OSO3M2), a sulfosuccinate or an ester salt, and an organic phosphonate, and water, and that is used for cleaning the surface having copper wiring after the CMP. R1 and R2 are alkyl groups with a carbon number of 1-6 or alkenyl groups with a carbon number of 2-6, and M1 and M2 are atoms other than hydrogen atoms or molecules that are to be cations.
The following literatures (Patent Literatures 5 and 6) do not describe that chemical products described in the respective Patent literatures are used as cleaning solutions; however, they describe that it is desirable to reduce the content of impurities such as alkali metal, regarding chemical products used in the field of a semiconductor device.
Patent Literature 5 discloses a method for producing an ionic polymer compound used preferably in the field in which the reduction of impurities is desired. The ionic polymer compound is obtained by treating an aqueous solution containing ionic low-molecular weight impurities and an ionic polymer compound having a salt-generating group with an ion exchange resin and thereafter, neutralizing the aqueous solution. The weight-average molecular weight of the ionic polymer compound is preferably 500 to 500,000.
Patent Literature 6 discloses a sulfocarboxylic acid agent containing sulfocarboxylic acid as a main component and further containing a trace amount of alkali metal. The sulfocarboxylic acid agent is used as an additive for a plating bath. Patent literature 6 discloses a problem that the insulation between circuits becomes defective when sodium ions remain in an electronic component, and that the content of alkali metal in the sulfocarboxylic acid agent is reduced using the ionic exchange resin.